1. Field of the Invention
The present invention is directed toward a pneumatic actuator for a gear reduction assembly for the landing gear of the trailer. The pneumatic actuator replaces the hand crank which has traditionally been used to raise or lower the feet of the truck trailer. Air pressure generated by the tractor and passed through the length of a brake line of the trailer drives the actuator. The present invention can be incorporated onto the already existing gear reduction assembly of the trailer landing gear or the present invention can be milled directly onto the newly manufactured trailer's gear reduction assembly.
2. Description of the Previous Art
a) U.S. Pat. No. 4,116,315 (Vandenberg) discloses a pneumatic landing gear actuator secured to the bottom of the trailer having a cross shaft running therethrough coupled to a first and a second rotable member which raises or lowers the landing gear feet dependent upon the direction the cross shaft is powered. Vandenberg requires two oppositely placed one way clutches (Sprague clutch) having slidable inner and outer driven members for engaging and rotating the cross shaft wherein the inner driven member is provided with spline gear for co-acting with meshing spline gear attached to cross shaft. Additionally, Vandenberg requires a shifting gear for regulating the direction the Sprague clutch driven members rotate the cross shaft turning the rotable members which raise or lower the landing gear feet. Further, Vandenberg requires a piston rod coupled to the pneumatic actuator housing at a first end and a radial arm at a second end wherein the radial arm turns the tube which simultaneously and synchronously rotates the Sprague clutch and the cross shaft passing between the clutch members in a ratchet-like manner.
b) U.S. Pat. No. 4,281,852 (Konkle) discloses a piston driven pneumatic actuator having first and second sets of lever arms including reciprocating pawls for engaging the toothed wheel of the actuator rod for raising or lowering trailer feet. Konkle requires each pawl to be swingably mounted to the lever arms and that each pawl has a body, a shoulder central to the body, depending fingers directed toward the periphery of the toothed wheel and springs for maintaining each pawl in a forward or reverse over-centered relationship with the tooth wheel for providing continuous forward or reverse direction in response to each movement of the actuator rod.
c) U.S. Pat. No. 4,400,986 (Swanson, et. al.) discloses a pneumatic landing gear actuator having first and second gears in a rotatable meshing arrangement for coupling with a rotable member for raising or lowering the feet of a trailer depending upon the direction of rotation. Further, Swanson requires that the first and second gears be engaged by first and second one-way ratchet wheels interacting with first and second pawls associated with first and second ratchet wheels, respectively, with each pawl being mounted on the pneumatic drive member that reciprocates back and forth. The spring assisted back and forth motion of Swanson produces the force for turning the rotable member which raises or lowers the feet of the trailer.
d) U.S. Pat. No. 4,402,526 (Huetsch), having common ownership with U.S. Pat. No. 4,400,986, discloses a landing gear actuator virtually identical to that of the Swanson reference which must be mounted outboard of a foot of the trailer. Additionally, the Huetsch disclosure has required the elements of a fixed angular relationship between the cross shaft and the crankshaft with the cross shaft being defined as the output and the crankshaft being defined as the input. Further, Huetsch requires a reciprocating piston for turning the rotatable member that is coupled to crankshaft which through the gearing mechanism rotates the crankshaft which raises and lowers the trailer feet.
e) U.S. Pat. No. 4,466,637 (Nelson) discloses an electric power drive combination for a trailer landing gear wherein the power drive combination is mounted axially to and coupled with the input shaft of the gear reduction assembly.